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Organic Chemistry
Introduction to Organic Chemistry
What is Organic Chemistry?
Organic Chemistry is the study of carbon
containing compounds
Organic compound
– Is molecular compound of carbon
– Is made up of carbon and hydrogen exclusively
(hydrocarbons) or carbon, hydrogen and small
amount of other elements such as N,P,O,S and
halogen atoms (hydrocarbon derivatives)
What is Inorganic Chemistry?
Inorganic Chemistry is the study of the rest of the elements
Examples of Organic Compounds
– Sugar, fat, oil, protein, starch
– Clothing - wool, silk, cotton, nylon, spandex, acrylic fabrics
– Cosmetics – creams, perfumes
– Medicine
– Plastic, rubber, paints
– Pesticides, herbicides
Compounds found in nature
– Produced through process called biosynthesis
– Sugar, cotton, wool…
Compounds made by man
– Synthetic compounds
– Nylon, rubber, creams
History of Organic Chemistry
Historically, organic compounds were obtained naturally from living organisms (plants and animals)
1828 – Fridrich Wohler synthesized first organic compound (urea) from inorganic reactants
We now have found ways of synthesizing these organic compounds (with the desirable properties of the natural compounds)
Synthesis of New Organic Compounds
Synthesis from elemental carbon and hydrogen (other elements) is not always possible
Majority of organic compounds is synthesized from other organic compounds (hydrocarbons)
Sources of hydrocarbons
– Wood
– Products that result from fermentation of plants
– Fossil fuels (origins in organic matter)
Coal
Petroleum (crude oil)
Natural gas
Petroleum
Main source of the hydrocarbons that are used for fuels and many other products (eg. Plastic and synthetic fabric)
Mixture of solid, liquid and gaseous hydrocarbons
Petroleum is process at oil refineries (fractional distillation)
Sooo.. Many organic compounds
There are approximately 6 times as many organic compounds as there are inorganic compounds
Why is this so?
Why is Carbon so Special?
The unique characteristics of carbon allow for large number of organic compounds
Carbon forms a total of four covalent bonds
Thus it can bond to itself or many different atoms
Carbon atoms can bond together to form a variety of geometrical structures
Forms single, double or triple bonds
Representing Organic Compounds
Organic compound
Structural diagrams
Condensed structural diagram
Complete structural diagram
Line structural formula
Skeletal structure
Molecular formula Structural models
Ball-and-stick models
Space-filling models
Dash-wedge-line structures
Molecular formula
Shows the actual number of atoms of each element in a molecule
Disadvantage : it does not provide information about structure
Eg. Draw a skeletal structure of pentane, C5H12 .
Isomers
Are compounds with the same molecular formula but different molecular structures
Named differently
Have different physical and chemical properties
Structural diagrams
Also called structural formulas
Are two dimensional representation of the arrangement of the atoms in molecules
Advantages: gives complete information about the arrangement of atoms in a molecule
Disadvantages: does not provide information about the spatial orientation of atoms
Complete Structural Diagram
Also called expanded structural diagram
Shows all the atoms in a structure and how they are bonded to one another
Bonds are shown with straight lines
Disadvantage?
“—” A single line represents one pair of electrons (a single bond)
“=” A double line represents two pairs of electrons (a double bond)
“≡” A triple line represents three pairs of electrons (a triple bond)
Condensed Structural Diagram
Shows the kind and number of atoms present
Only shows bonds between carbon atoms
The bond between hydrogen and carbon is assumed to be present
Expanded Molecular Formula
Shows groupings of atoms without drawing lines to show the actual bonds that occur, they are assumed to be present
Brackets are used to indicate the location of branched chains
Line Structural Diagram
The end of each line, and the points where lines meet, represent carbon atoms
Hydrogen atoms are assumed to be present in the correct number
Gives you a sense of the three-dimensional nature of the bonds
Representing Structures
Complete Structural Diagram
Condensed Structural Diagram
Expanded Molecular Formula
Line Structural Diagram
CH3–CH2–CH2–CH3
CH3CH2CH2CH2CH3
Common molecular shapes in organic chemistry
Classifying Hydrocarbons
Chemists group hydrocarbons and other organic compounds into categories based on their properties
The International Union of Pure and Applied Chemistry (IUPAC) developed a set of rules for naming the compounds in each category
Organic Compounds
Hydrocarbons
Aliphatic
Hydrocarbons
Saturated Hydrocarbons
Alkanes
Unsaturated Hydrocarbons
Alkenes Alkynes
Alicyclic
Hydrocarbons
Aromatic
Hydrocarbons
Hydrocarbon Derivatives
Terms To Know
Saturated
organic compounds in which each carbon atom is bonded to the maximum number of hydrogen atoms, thus containing only single bonds
Unsaturated
organic compounds in which the carbon atoms do not have the maximum number of hydrogen atoms and thus have double or triple bonds
Classifying Hydrocarbons
Look at the following compounds. If you were to classify them, how would you do it?
Single Bond Compounds
These are called Alkanes!
Double Bond Compounds
These are called Alkenes!
Triple Bond Compounds
These are called Alkynes!
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